A. The wavelength of microwaves is greater than that of UV-rays.

B. The wavelength of IR rays is lesser than that of UV-rays.

C. The wavelength of microwaves is lesser than that of IR-rays.

D. Gamma rays have shortest wavelength in the Electromagnetic Spectrum.

Of the above statements

A and D are true

The wavelength order of the given types of waves are given below

Waves Wavelength Range (in meter)

Gamma rays IR-rays   10⁻¹⁴ −10⁻¹⁰

IR-rays                       7 × 10⁻⁷ = 10⁻³

UV-rays                     10⁻⁹ − 4 × 10⁻⁷  

Microwave                 10⁻⁴ − 10⁰      

Hence, statements (A) and (D) are correct.